Conventional content delivery networks (CDNs) provide access methods to published data objects, such as documents, files, graphical entities, and other media. In such a network, data is typically written once and retrieved many times by a plurality of users. For example, a large corporation may establish a CDN for customer service, operable to store entities such as user manuals, FAQs (frequently asked questions), technical service bulletins, historical reference documents for obsolete products, and other support items. A content provider typically outsources a conventional CDN to a service provider host responsible for maintaining the CDN. A service level agreement (SLA) defines the responsibilities of the CDN host to provide timely content to requesting users, and defines specific performance criteria that the host will achieve for retrieval requests. For example, a SLA may specify that a CDN website is to respond to a volume of 1000 requests an hour each in 5 seconds or less.
A similar model is applicable to a long-term archive or backup environment. A system operator or other support entity typically provides backup for conventional information systems according to a periodic schedule to guard against data loss from accidental deletions, hardware failure, and user error. Often, an organization delegates the archive task to a third party according to an SLA. A conventional SLA may specify a certain volume of data and duration of archive during which the archiver is expected to maintain and retrieve requested data as needed.
One method of providing content is shown by “FreeFlow”, a CDN product marketed commercially by Akamai Technologies, Inc. of Cambridge Mass. FreeFlow establishes a CDN including fast access cache servers which store content of requested web pages to offload processing demands from hits on a main target website. This system uses fingerprinting of the data to identify and maintain cache copies in the fast access cache servers distinct from the main website. The FreeFlow system, therefore, maintains high speed cache data proximate to a requester, and invokes fingerprinting to avoid staleness of the data. Therefore, the FreeFlow system appears to identify the content of the web page data for fast access, independently of an association to other extrinsic data or information objects.
Other systems that purport to provide backup services include STORos storage manager for backup, available commercially by StorageNetworks of Waltham, Mass., which suggests a unified view of backup architectures across multiple backup servers, software packages, and locations. Another entity concerned with services according to SLAs includes Scale8, Inc. of San Francisco, Calif., which provides Scale8 Global Storage Service and a family of Network-Attached Storage (NAS) products.